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| Ardhuin, Fabrice; Gualtieri, Lucia; Stutzmann, Eleonore. |
| Microseismic activity, recorded everywhere on Earth, is largely due to ocean waves. Recent progress has clearly identified sources of microseisms in the most energetic band, with periods from 3 to 10 s. In contrast, the generation of longer-period microseisms has been strongly debated. Two mechanisms have been proposed to explain seismic wave generation: a primary mechanism, by which ocean waves propagating over bottom slopes generate seismic waves, and a secondary mechanism which relies on the nonlinear interaction of ocean waves. Here we show that the primary mechanism explains the average power, frequency distribution, and most of the variability in signals recorded by vertical seismometers, for seismic periods ranging from 13 to 300 s. The secondary... |
| Tipo: Text |
Palavras-chave: Hum; Infragravity waves; Numerical model; Microseisms. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00251/36219/34769.pdf |
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| Deen, M.; Wielandt, E.; Stutzmann, Eleonore; Crawford, W.; Barruol, G.; Sigloch, K.. |
| The Earth's hum is the permanent free oscillations of the Earth recorded in the absence of earthquakes, at periods above 30 seconds. We present the first observations of its fundamental spheroidal eigenmodes on broadband Ocean Bottom Seismometers (OBS) in the Indian Ocean. At the ocean bottom, the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In our experiment, data are also affected by electronic glitches. We remove these signals from the seismic trace by subtracting average glitch signals; performing a linear regression and using frequency-dependent response functions between pressure, horizontal and vertical seismic components. This reduces the long period noise on the OBS to the level of a good land... |
| Tipo: Text |
Palavras-chave: Hum; Noise; Continuous oscillations; Broadband ocean bottom seismology; Surface waves; Glitch. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00407/51841/52446.pdf |
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